继续上一篇http://blog.csdn.net/acmman/article/details/43889483的介绍
3.注解@Required
是初始化的时候就给注入,检查这个配置是否有问题。用来容错的。
4.@Resource(重要)
a)加入:j2ee/common-annotation.jar
@Resource是j2ee的标准。
b)默认按名称,名称找不到,按类型(比AutoWired更直观)
beans.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <bean id="u" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="1"></property> </bean> <bean id="userService" class="cn.edu.hpu.service.UserService"> </bean> </beans>
UserService.java:
package cn.edu.hpu.service; import javax.annotation.Resource; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserService { private UserDao userDao; public void init(){ System.out.println("init"); } public UserDao getUserDao() { return userDao; } @Resource public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void add(User u){ this.userDao.save(u); } public void destroy(){ System.out.println("destroy"); } }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); System.out.println(userService.getUserDao()); ctx.destroy(); } }
结果:
daoid=1
c)可以指定特定名称
beans.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <bean id="u" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="1"></property> </bean> <bean id="u2" class="cn.edu.hpu.dao.Impl.UserDaoImpl"> <property name="daoId" value="2"></property> </bean> <bean id="userService" class="cn.edu.hpu.service.UserService"> </bean> </beans>
UserService.java中改一下这里
@Resource(name="u2") public void setUserDao(UserDao userDao) { this.userDao = userDao; }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); System.out.println(userService.getUserDao()); ctx.destroy(); } }
结果:
daoid=2
d)推荐使用
原因是比比AutoWired更直观
e)不足:如果没有源码,就无法运用annotation,只能用xml.
5.@Component(spring自带)
如果不想在beans.xml里面写bean了,想一劳永逸,让spring去指定包下去寻找,那么就用
<context:component-scan base-package="XXXX">其中"XXXX"就是指定的包名。
实验:
beans.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <context:component-scan base-package="cn.edu.hpu"/> <bean id="userService" class="cn.edu.hpu.service.UserService"> </bean> </beans>
UserDaoImpl.java:
package cn.edu.hpu.dao.Impl; import java.util.List; import java.util.Map; import java.util.Set; import org.springframework.stereotype.Component; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; @Component public class UserDaoImpl implements UserDao{ public void save(User u) { System.out.println("add success!!"); } }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); User u=new User(); u.setUsername("u1"); u.setPassword("p1"); userService.add(u); ctx.destroy(); } }
结果:
add success!!
a)初始化的名字默认为类名字母小写
推荐写上名字
beans.xml:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"> <context:annotation-config/> <context:component-scan base-package="cn.edu.hpu"/> </beans>
UserService.java:
package cn.edu.hpu.service; import javax.annotation.Resource; import org.springframework.stereotype.Component; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; @Component("userService") public class UserService { private UserDao userDao; public void init(){ System.out.println("init"); } public UserDao getUserDao() { return userDao; } @Resource(name="u") public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void add(User u){ this.userDao.save(u); } public void destroy(){ System.out.println("destroy"); } }
UserDaoImpl.java:
package cn.edu.hpu.dao.Impl; import java.util.List; import java.util.Map; import java.util.Set; import org.springframework.stereotype.Component; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; @Component("u") public class UserDaoImpl implements UserDao{ public void save(User u) { System.out.println("add success!!"); } }
测试:
package cn.edu.hpu.service; import org.junit.Test; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import cn.edu.hpu.dao.UserDao; import cn.edu.hpu.model.User; public class UserServiceTest { @Test public void testAdd() throws Exception{ ClassPathXmlApplicationContext ctx=new ClassPathXmlApplicationContext("beans.xml"); UserService userService=(UserService)ctx.getBean("userService"); User u=new User(); u.setUsername("u1"); u.setPassword("p1"); userService.add(u); ctx.destroy(); } }
结果:
add success!!
b)可以指定初始化bean的名字
目前@Component、@Repository(数据仓库)、@Service、@Controller没有区别
有源码用Annotation方便,开发效率高,没源码用XML。
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